Smart Contract Encapsulator (SCE)

The Smart Contract Encapsulator (SCE) is a core component of the NebulOuS SLA lifecycle.
It consumes SLAs produced by the SLA Generator, converts them into deterministic smart contract states, and stores them on a Hyperledger Fabric ledger via the Fabric Gateway (FGW).

Additionally, the SCE ingests real-time monitoring events, evaluates SLA conditions, detects violations, triggers state transitions and settlements, and publishes events back to AMQP message topics for system-wide consumption.

Features

Deterministic & Tamper-Proof Contracts

Every SLA is transformed into a deterministic smart contract state, ensuring that all endorsing peers produce identical results. This guarantees immutability, auditability, and trust in SLA commitments.

Real-Time Violation Detection

The SCE continuously consumes monitoring data streams and performs on-chain evaluation of metrics against SLA rules.
Violations are detected instantly, minimizing the gap between SLA breaches and remediation.

Automated Lifecycle Transitions

SLAs evolve dynamically as metrics change.
The SCE applies state transitions (e.g., SLA moving from sl 1 → sl 2 → sl 3) and triggers settlements automatically.

Event-Driven Integration

The SCE emits structured Fabric events (Violation, Transition, Settlement) and republishes them to AMQP topics.
This ensures that SLA status updates are instantly available to the entire NebulOuS ecosystem.

Key Components

• Certificate Authority

  Manages digital identities and cryptographic materials (MSP, TLS certificates) for all network participants.

• Fabric Network

  Consists of an ordering service and peer nodes from different organizations.

• Smart Contract (Chaincode)

  Java-based chaincode that manages SLA lifecycle, violations, transitions, and settlements on the ledger.

• SCE Application

  Client application that connects to the Fabric network, validates SLA JSON, processes monitoring events, and publishes Fabric events to AMQP topics.

Installation & Setup

Prerequisites

Before setting up the SCE, ensure the following are installed:

• Docker (20.10+)
• Docker Compose (1.29.2+)
• Java JDK (11+)
• Maven (3.6+)
• Hyperledger Fabric binaries and Docker images (v2.5.5)

Certificate Authority Setup

Before running the application, you need to create the required certificates for each organization and place them in the appropriate wallet directories.

Enroll Organizations and Generate Certificates

Use the following Docker commands to enroll each organization and generate the necessary certificates.

docker service create --name enroll-<ORG_NAME> \
  --network fabric-ca_fabric-ca \
  --secret <CA_BOOTSTRAP_PW_SECRET> \
  --secret postgres_password \
  --mount type=bind,src=/home/ubuntu/smart-contract-encapsulator/nebulous-certificate-authority,dst=/workspace \
  -w /workspace/scripts \
  -e ROOT_DIR=/workspace \
  -e CA_SERVICE_NAME=<CA_SERVICE_NAME> \
  -e CA_PORT=<CA_PORT> \
  -e FABRIC_LOGGING_SPEC=debug \
  --replicas 1 \
  --restart-condition none \
  --constraint 'node.role == manager' \
  local/fabric-ca-client:alpine \
  sh -c "fabric-ca-client version && bash <ENROLL_SCRIPT>.sh"

Create Wallet Directories and Place Certificates

After enrolling each organization, you need to organize the generated certificates and private keys into your application’s wallet structure. Create the necessary directories:

# Identity certificates and keys for each user
mkdir -p wallet/<USER>@<ORG>/msp/signcerts
mkdir -p wallet/<USER>@<ORG>/msp/keystore

# TLS certificates
mkdir -p wallet/certs

Place the certificates in the appropriate folders:

• User identity certificate → wallet/@/msp/signcerts/cert.pem
• User private key → wallet/@/msp/keystore/ (keep the original file name)
• TLS CA certificates → wallet/certs/ (rename as needed for each peer/orderer, e.g., tlsca.-cert.pem or peer0..tls.ca.crt)

Build the application

mvn clean package

Build Docker image

docker build -t nebulous-sce-application:latest .

Running the Application

Start the SCE application with the following command:

docker run --rm --network host \
  -v /home/ubuntu/smart-contract-encapsulator/nebulous-sce-application/wallet:/usr/local/lib/wallet:ro \
  nebulous-sce-application:latest \
  --activemq-host localhost \
  --activemq-port 5672 \
  --activemq-user admin \
  --activemq-password admin

Application Parameters

--activemq-host: ActiveMQ broker hostname

--activemq-port: ActiveMQ broker port (default: 5672)

--activemq-user: ActiveMQ username

--activemq-password: ActiveMQ password